Does SDKMAN supports java SDKs only? We don't plan to add support for language specific package managers.

From their website, I quote:

Install Software Development Kits for the JVM such as Java, Scala, Kotlin, and Groovy. Ant, Gradle, Grails, Maven, SBT, Spark, Spring Boot, Vert.x and many others also supported.

So, technically no. It is not only Java Development Kits (JDKs), but rather SDKs for Java Virtual Machine (JVM) and then some more. For example:

1. Apache Spark, for example, is built using Scala (a JVM functional programming language). While the engine itself is written in Scala, it offers high-level APIs in multiple programming languages, including Java, Python (via PySpark), R, and Scala, allowing developers to write applications in their preferred language.
2. Apache ActiveMQ is primarily written in Java and is a Java-based message broker developed by the Apache Software Foundation. While the core broker is Java-based, Active's supports clients written in a wide range of programming languages, including JavaScript, C, C++, Python, .NET, Ruby, PHP, and others.

We don't plan to add support for language specific package managers.

The Java equivalent for npm is not SDKMAN!. It would be rather maven and gradle, which happen to be installable via apt as well as SDKMAN!.

My point is: This is not to install Java project libraries like npm or pip.

I laid my case. It is up to the maintainers and the community from here.